蜂巢式IP網路利用群組網路的概念解決行動IP的缺點。當行動電腦在相同的群組網路下移動時，不需要向主代理者註冊，而是向較近的群組主電腦報告，因而省下傳輸時間，使得行動電腦在不同基地台間的換手過程更為迅速。然而，在蜂巢式IP網路下只有一個群組主電腦，一旦群組主電腦當機或發生故障，行動電腦之通訊也會隨之中斷。目前相關的研究則使用備份電腦，不過這種方式並不能解決網路分割的情況。
　　本篇論文是在同一個群組網路使用多個群組主電腦，他們彼此之間會定期地偵測錯誤，包括網路分割或主電腦損壞等。錯誤發生時，運作正常的電腦會根據錯誤的種類而做處理，直到系統復原後，再將工作移轉回原電腦。在實作方面，將探討本機制所會產生的負擔與影響，而依據結果，本機制可以避免行動電腦重新註冊進而減少資料的遺失且不會降低蜂巢式IP網路的效能。

　　The Cellular IP protocol provides better performance for hando® than other protocols using micro-mobility. A set of base stations cluster together on the same cellular IP network. This kind of domain-based network is superior to Mobile IP in support of route optimization and quality of service (QoS). However, there is a single point of failure in cellular IP. If the gateway fails, services will break down for mobile nodes, even though there are other gateways at the same domain network.
　　This thesis develops a fault detection mechanism and a recovery protocol for cellular IP. When one gateway fails or network partition occurs, another gateway will detect and continue providing services. For providing higher reliability, all gateways, even they are in di®erent networks, coordinate with each other and act as a virtual gateway. The mobile nodes transparently use this virtual gateway as its foreign agent or home agent. Experiments were conducted to explore the load of our protocol and survey the packet lost. These results show that the load of control packets is negligible for cellular IP and the number of the lost packets can be successfully reduced.

[1] C. Perkins, “IP Mobility Support,” RFC 2002, Oct. 1996.

[2] E. Gustafsson, A. Jonsson, and C. Perkins, “Mobile IP Regional Registration,” (work in progress), July 2000.

[3] C. Perkins and D. Johnson, “Route Optimization in Mobile IP,” (work in progress), Nov. 2000.

[4] A. T. Campbell, J. Gomez, S. Kim, C. Y. Wan, Z. R. Turanyi, and A. G. Valko, “Comparison of IP Micromobility Protocols,” IEEE Wireless Communications, vol. 9, pp. 72–82, Feb. 2002.

[5] R. Ramjee, T. L. Porta, S. Thuel, K. Varadhan, and S. Y. Wang, “HAWAII: A Domain-based Approach for Supporting Mobility in Wide-area Wireless Networks,” Proceedings of the Seventh International Conference on Network Protocols, pp. 283–292, Oct. 1999.

[6] A. G. Valko, A. T. Campbell, and J. Gomez, “Cellular IP,” Internet Draft, Nov. 1999.

[7] A. T. Campbell, J. Gomez, S. Kim, A. G. Valko, C. Y. Wan, and Z. R. Turanyi, “Design, implementation, and evaluation of Cellular IP,” IEEE Personal Communications, vol. 7, pp. 42–49, Aug. 2000.

[8] E. Gustafsson, A. Jonsson, and C. Perkins, “Mobile IP Regional Registration,” Internet Draft, July 2000.

[9] B. Chambless and J. Binkley, “HARP-Home Agent Redundancy Protocol,” Internet Draft, Oct. 1997.

[10] J. R. Binkley and J. McHugh, “Secure Mobile Networking-Final Report,” Portland State University, June 1999.

[11] J. Ahn and C. Hwang, “E±cient Fault-tolerant Protocol for Mobility Agents in Mobile IP,” Proceedings of the 15th International Parallel and Distributed Processing Symposium, pp. 1273–1280, Apr. 2001.

[12] T. Li, B. Cole, P. Morton, and D. Li, “Cisco Hot Standby Router Protocol (HSRP),” RFC 2281, Mar. 1998.

[13] C. Perkins, “IP Encapsulation within IP,” RFC 2003, Oct. 1996.

[14] C. Perkins, “Minimal Encapsulation within IP,” RFC 2004, Oct. 1996.

[15] The Network Simulator, http://www.isi.edu/nsnam/ns/.

[16] H. Haverinen and J. Malinen, “Mobile IP Regional Paging,” Internet Draft, July 2000.

[17] S. Paskalis, A. Kaloxylos, and E. E. Zervas, “An e±cient QoS scheme for mobile hosts,” Proceedings of the 26th Annual IEEE Conference on Local Computer Networks(LCN), pp. 630–637, Nov. 2001.

[18] S. U. Yoon, J. H. Lee, K. S. Lee, and C. H. Kang, “QoS support in mobile/wireless IP networks using di®erentiated services and fast hando® method,” Wireless Communications and Networking Confernce(WCNC), vol. 1, pp. 266–270, Sept. 2000.